Cryogenic Container, Superconductivity Magnetic Energy Storage (SMES) System, And Method For Shielding A Cryogenic Fluid

ABSTRACT

A cryogenic container includes an inner vessel for containing a cryogenic fluid, and an outer vessel for insulating the cryogenic fluid from the environment. The inner vessel includes a superconductive layer formed of a material having superconducting properties at the temperature of the cryogenic fluid. The superconductive layer forms a magnetic field around the cryogenic container, that repels electromagnetic energy, including thermal energy from the environment, keeping the cryogenic fluid at low temperatures. The cryogenic container has a portability and a volume that permits its&#39; use in applications from handheld electronics to vehicles such as alternative fueled vehicles (AFVs). A SMES storage system includes the cryogenic container, and a SMES magnet suspended within the cryogenic fluid. The SMES storage system can also include a recharger and a cryocooler configured to recharge the cryogenic container with the cryogenic fluid.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of Ser. No. 11/132,135 filed May 18,2005.

FIELD OF THE INVENTION

This invention relates generally to cryogenic containers for storingcryogenic fluids. This invention also relates to superconductivitymagnetic energy storage (SMES) using cryogenic containers. Thisinvention also relates to methods for shielding cryogenic fluids fromthermal energy.

BACKGROUND OF THE INVENTION

Cryogenic containers, such as dewar type containers and cryogenic tanks,are used to store cryogenic fluids such as liquid nitrogen, oxygen,hydrogen and neon. A conventional cryogenic container includes an innertank configured to contain the cryogenic fluid, and an outer tankconfigured to provide a thermal barrier between the cryogenic fluid andthe environment. In addition, the outer tank forms an annulus around theinner tank in which insulation, and in some systems a vacuum, iscontained. The outer tank and the annulus are constructed to minimizethe conduction of thermal energy from the environment to the cryogenicfluid.

Cryogenic containers are commonly used by hospitals and in industrialapplications where portability and compactness are not primaryconsiderations. Cryogenic containers are also used in the transportationindustry on ships and vehicles such as tank trucks and rail cars. In thetransportation industry, portability and compactness are more of anissue, but in view of the scale of the vehicles, are not primaryconsiderations.

Cryogenic containers are also used in alternative fueled vehicles(AFVs), such as cars and trucks, to store a cryogenic fluid for use as acombustion fuel for the vehicles. In this case, the cryogenic fluid canbe in the form of liquid natural gas (LNG), compressed natural gas (CNG)or liquefied petroleum gas (LPG). The development of alternative fueledvehicles (AFVs) has been spurred by the Clean Air Act (1990) and theEnergy Policy Act (1992). In addition, developing economies, such asChina, have opted for polices which favor alternative fueled vehicles(AFVs) over conventional gas and diesel vehicles. With alternativefueled vehicles (AFVs), the portability and compactness of a cryogeniccontainer can be a primary consideration. In addition, because thecryogenic liquids must be stored for periods of days or longer, thesecryogenic containers must have a high thermal resistance from theenvironment to the cryogenic fluid.

Another technology that employs cryogenic containers is low temperaturesuperconductivity. Superconductive materials have the ability to conductelectrical currents with no energy losses or resistive heating. Inaddition, superconductive materials exhibit magnetic properties thatallow magnetic fields in excess of 20 tesla to be produced. Lowtemperature superconducting magnets are used in magnetic resonanceimaging systems for medical applications, and in laboratories forexperimental applications. In these applications, cryogenic containersare employed to maintain the low temperatures necessary forsuperconductivity.

Recently, superconductors, such as magnesium diboride (MgB₂), have beendiscovered which exhibit superconductivity at temperatures approaching40 K. Although this is a low temperature, it can be achieved usingtechnologies that are less expensive than those used to achievesuperconductivity in conventional superconductors, such as niobiumalloys, which require temperatures of about 23° K.

In addition to their use in magnetic resonance imaging systems,superconducting magnets can be used for storing electrical energy. Thistechnology is known as superconducting magnetic energy storage (SMES).For example, U.S. Pat. No. 5,146,383 to Logan entitled “ModularSuperconducting Magnetic Energy Storage Inductor”, discloses a SMESsystem. U.S. Pat. No. 6,222,434 B1 to Nick entitled “SuperconductingToroidal Magnet System” also discloses a SMES system. In general, theseprior art SMES systems are large non-portable, devices which arehundreds of feet in diameter. This technology, could be adapted totransportation and AFV industries, and to other applications as well, ifthe scale of the SMES system could be reduced.

The present invention is directed to all sizes of cryogenic containers,but particularly to a cryogenic container that is portable, yet has alow thermal conductivity, and a high thermal shielding capability.Further, the present invention is directed to a portable SMES systemconstructed using the cryogenic container. Still further, the presentinvention is directed to improved methods for shielding a cryogenicfluid from thermal energy.

SUMMARY OF THE INVENTION

In accordance with the present invention, an improved cryogeniccontainer, a SMES system, and an improved method for shielding acryogenic fluid are provided.

The cryogenic container includes an inner vessel configured to containthe cryogenic fluid at a selected temperature range. The cryogeniccontainer also includes an outer vessel surrounding the inner vessel,and an annulus between the inner vessel and the outer vessel configuredto contain an insulating material and/or a vacuum. The inner vesselincludes a superconducting layer formed of a material havingsuperconductive properties at the selected temperature range.

In the illustrative embodiment the inner vessel comprises a metalcylinder, and the superconducting layer covers either an inner surface(ID), or an outer surface (OD) of the inner vessel. Preferably, thesuperconducting layer comprises a low temperature superconductormaterial, such as magnesium diboride, a niobium alloy, a copper oxide ora BCS superconductor. The superconducting layer creates a magneticfield, which shields the cryogenic fluid from electromagnetic energy,reducing heat transfer from the environment, and maintaining thecryogenic fluid at low temperatures.

Heat transfer in the cryogenic container is affected by a number offactors, including, but not limited to, the infrared heating of the coldsurfaces, conductive heat transfer by gas molecules from warm surfacesto cold surfaces, and conductive heat transfer through the supportstructure for the inner vessel. The magnetic field created by thesuperconducting layer reduces heat transfer due to infrared heating ofthe cold surfaces. The insulation in the annulus also reduces heattransfer from the environment to the cryogenic fluid.

The SMES system includes the cryogenic container and a SMES magnet inthe inner vessel configured to store electrical energy. The SMES systemalso includes an electrical connector on the outer vessel configured forconnection to an energy source for transferring electrical energy intothe SMES magnet, or to a load for extracting stored electrical energyfrom the SMES magnet. The SMES system can also include a recharger and acryocooler configured to recharge the cryogenic container with thecryogenic fluid.

The method includes the steps of: providing the cryogenic containeradapted to contain the cryogenic fluid at the selected temperaturerange, providing the layer on the cryogenic container havingsuperconductive properties at the selected temperature range, andshielding the cryogenic fluid from electromagnetic energy using thelayer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic cross sectional view of a cryogenic containerconstructed in accordance with the invention;

FIG. 1B is a schematic cross sectional view of the cryogenic containertaken along section line 1B-1B of FIG. 1A;

FIG. 1C is an enlarged schematic cross sectional view taken alongsection line 1C-1C of FIG. 1B illustrating a superconductor layer on aninner wall of the cryogenic container;

FIG. 1D is an enlarged schematic cross sectional view taken alongsection line 1D-1D of FIG. 1B illustrating a superconductor layer on anouter wall of the cryogenic container;

FIG. 2A is a schematic cross sectional view of a SMES system constructedin accordance with the invention using the cryogenic container;

FIG. 2B is a schematic cross sectional view of the SMES system takenalong section line 2B-2B of FIG. 2A;

FIG. 2C is an enlarged schematic cross sectional view taken alongsection line 2C-2C of FIG. 2B illustrating a superconductor layer on theSMES system;

FIG. 2D is an enlarged schematic cross sectional view taken alongsection line 2D-2D of FIG. 2B illustrating the superconductor layer onthe SMES system

FIG. 3 is an electrical schematic of a SMES magnet of the SMES system;and

FIG. 4 is a block diagram illustrating steps in the method of theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1A-1D, a cryogenic container 10 constructed inaccordance with the invention is illustrated. The cryogenic container 10includes an outer vessel 12, and an inner vessel 14 suspended within theouter vessel 12. The outer vessel 12 and the inner vessel 14 and aregenerally cylindrically shaped, fluid tight tanks having internalvolumes selected as required. Rather than being cylindrical, the outervessel 12 and the inner vessel 14 can have other shapes, such ascylindrical.

Both the outer vessel 12 and the inner vessel 14 can comprise anymaterial commonly used in the construction of Dewar-type cryogenictanks, such as steel, stainless steel, or non magnetic stainless steel.In addition, the inner vessel 14 can be suspended within the outervessel 12 using any conventional structure, such as support rods orrings (not shown).

Since size of the cryogenic container 10 is a key to portability, it ispreferred that for portable applications, the cryogenic container 10 befrom 1 centimeter to 1 meter in diameter, and 5 centimeter to 2 metersin length. However, these dimensions are not fixed and for non portableapplication can be increased to hundreds of feet. In addition, forportable applications, the cryogenic container 10 can be adapted tocontain a volume of from 10 cc (cubic centimeters) to 1 m³ (cubicmeters) of a cryogenic fluid 16. In general, container sizes larger thanthis range adversely affect the portability of the cryogenic container10, and its' use in transportation systems, particularly alternativefueled vehicles (AFVs). However, for non portable applications thecontained volume can be greatly increased as the dimensions of thecryogenic container 10 are increased.

As shown in FIGS. 1A and 1B, the cryogenic fluid 16 is contained withinthe inner vessel 14. As used herein “cryogenic fluid” refers to fluidhaving a temperature of between 0.001 K and 200 K. Depending on theapplication, the cryogenic fluid 16 can comprise any fluid at cryogenictemperatures. By way of example, and not limitation, representativecryogenic fluids include nitrogen, oxygen, hydrogen, neon and compoundsof these elements. In the illustrative embodiment, the cryogeniccontainer 10 is oriented in a horizontal direction (i.e., parallel tothe ground), such that the cryogenic fluid 16 has a fluid level 20 whichis generally horizontal, and parallel to a longitudinal axis 15 of thecryogenic container 10. Alternately, the cryogenic container 10 can bevertically oriented, in which case the fluid level 20 would be generallyorthogonal to the longitudinal axis 15.

The cryogenic container 10 also includes an annulus 18 between the outervessel 12 and the inner vessel 14. The annulus 18 is adapted to containa vacuum, and a multilayer thermal insulation 17, such as an A1/mylarand Dacron netting. The cryogenic container 10 also includes aninterface tube 23, extending along the longitudinal axis 15 acrossnearly the entire length thereof. The interface tube 23 can includecontrol devices, such as sensors, and a shut off valve, and safetydevices, such as a pressure relief valve. The interface tube 23 cancomprise a material having a high strength to thermal conductivityratio, such as a fiberglass/epoxy composite. In addition, the interfacetube 23 can include an external vacuum jacket (not shown).

The cryogenic container 10 also includes a superconducting layer 22,which comprises a material having superconductive properties at atemperature range corresponding to that of the cryogenic fluid 16.Preferably, the superconducting layer 22 comprises a low temperaturesuperconductor where low temperature is defined as from 0.1 K to 150 K.Suitable low temperature superconductors include magnesium diboride,niobium alloys, and copper oxide alloys, such as rare earth copper oxide(RECuOx). Other suitable superconductors include carbon materials,ceramic materials and doped materials, such as magnesium diboride dopedwith silicon carbide (e.g., MgB₂Si_(x)). In general, the superconductivelayer 22 can comprise any BCS superconductor, where BCS represents theinitials of superconductor pioneers John Bardeen, Leon Cooper, andRobert Schrieffer. Further, the superconductive layer 22 can comprisemultiple layers of material, such as different superconductors havingdifferent magnetic or electrical characteristics.

As shown in FIG. 1C, the superconducting layer 22 can cover an outsidesurface 19 (i.e., outside diameter—OD), of the inner vessel 14.Alternately, as shown in FIG. 1D, the superconducting layer 22 can coveran inside surface 21 (i.e., inside diameter—ID) of the inner vessel 14.As another alternative, the superconducting layer 22 can cover both theoutside surface 19 and the inside surface 21 of the inner vessel 14.

The superconducting layer 22 can be formed on the inner vessel 14 usinga suitable coating, deposition or laminating process such as chemicalvapor deposition (CVD), mechanical alloying, or sintering. In addition,as previously stated, the superconducting layer 22 can comprise a singlelayer of material, or multiple stacked layers of material. A thickness Tof the superconducting layer 22 can be selected as required, with from0.1 μm to 1 meter being a representative range. Alternately, thesuperconductive layer 22 can comprise a separate element, such as acover or a lining, that encompasses or lines the inner vessel 14 but isnot permanently attached. In general, the superconductive layer 22 cancomprise any mass of superconductor material configured to provide ashielding structure for any part of the cryogenic fluid 20.

The superconducting layer 22 requires a low temperature in order toexhibit superconducting properties. For example, niobium-based alloysrequire a temperature of about 23 K to exhibit superconductingproperties. Magnesium diboride requires a relatively warm temperaturecompared to other superconductors of 40 K. In the present case, thesetemperatures are achieved when the superconducting layer 22 is cooled bythe cryogenic fluid 16.

For example, the cryogenic fluid 16 can be initially injected into theinner vessel 14 at a temperature of from 0.1 K to 150 K. This in turnwill cool the superconducting layer 22 to substantially the sametemperature. Once the superconducting layer 22 reaches its' criticaltemperature “Tc” and enters the superconducting state, a magnetic fieldwill be created around the cryogenic container 10. This magnetic fieldwill shield the cryogenic fluid 16 from electromagnetic energy,including thermal energy and infrared radiation, keeping the cryogenicfluid 10 at the desired low temperature. The superconducting layer 22thus prevents heat from being transmitted via radiation from theenvironment through the inner vessel 14 to the cryogenic fluid 16.

It is theorized by the inventor that the magnetic field created by thesuperconducting layer 22 inhibits the incoming electromagnetic energyvia either or both the Meissner effect, and/or pure diamagnetism. Thestrength of the magnetic field depends on the field strength, thecurrent density and the coherence of the superconducting layer 22. It isalso theorized that the repellent effect of the magnetic field createdby the superconducting layer 22 mitigates the heating effects of theincoming short wave radiation. The thermal insulation 17, in addition toproviding thermal insulation, also attenuates flux jumping and providesmagnetic stability for the magnetic field created by the superconductinglayer 22.

It is known that the superconducting state cannot exist in the presenceof a magnetic field greater than a critical value. This criticalmagnetic field is strongly correlated with the critical temperature ofthe superconductor material. It is the nature of superconductors toexclude magnetic fields so long as the applied field does not exceedtheir critical magnetic field. This critical magnetic field can betabulated at 0 K, and decreases from that magnitude as temperatureincreases, reaching zero at the critical temperature forsuperconductivity. The critical magnetic field at any temperature belowthe critical temperature is given by the relationship:B _(c) ≈B _(c)(0)[1−(T/T _(c))²]

where T represents the current temperature of the material, T_(c)represents the critical temperature of the material at which it which itloses its superconducting properties, and B_(c) (0) represents themagnetic field of the material at 0 K.

The Meissner effect states that when a material makes the transitionfrom a normal to a superconducting state, it actively excludes magneticfields from its interior. This constraint to zero magnetic field insidea superconductor is distinct from the perfect diamagnetism which wouldarise from its zero electrical resistance. With zero resistance, itwould be implied that if an attempt to magnetize a superconductor wasmade, current loops would be generated to exactly cancel the imposedfield. However, if the material already had a steady magnetic fieldthrough it when it was cooled through the superconducting transition,the magnetic field would be expected to remain. If there were no changein the applied magnetic field, there would be no generated voltage todrive currents, even in a perfect conductor. Therefore, the activeexclusion of magnetic field must be considered to be an effect distinctfrom zero resistance.

The superconducting layer 22 develops a magnetic field with frictionlesscurrent generation. The Meissner effect repels electromagnetic energy,including waves in the infrared region. The magnetic field enabled bythe cryogenic temperature of the cryogenic fluid 16 can have a strengthof up to 5 Telis. In addition, the energy requirement to maintain acurrent of 5 Telis is minimal because of the zero resistance nature ofthe superconductive field.

Referring to FIGS. 2A-2D, a SMES system 24 constructed in accordancewith the invention is illustrated. The SMES system 24 includes acryogenic container 26, which is substantially similar to the previouslydescribed cryogenic container 10 (FIG. 1A). The cryogenic container 26includes an outer vessel 28, an inner vessel 30, an annulus 32, andthermal insulation 33, substantially as previously described for theouter vessel 12 (FIG. 1A), the inner vessel 14 (FIG. 1A), the annulus 18(FIG. 1A), and the thermal insulation 17 (FIG. 1A). In addition, acryogenic fluid 34 having a fluid level 37 is contained within the innervessel 30, substantially as previously described for cryogenic fluid 16(FIG. 1A) and fluid level 20 (FIG. 1A). The cryogenic container 26 alsoincludes an interface tube 35, substantially as previously described forthe interface tube 23 (FIG. 1A).

The cryogenic container 26 (FIG. 2A) also includes a superconductinglayer 36 (FIGS. 2C-2D) formed on either an outside surface 29 (FIG. 2C)of the inner vessel 30 (FIG. 2C), or on an inside surface 41 (FIG. 2D)of the inner vessel 30 (FIG. 2D). The superconducting layer 36 (FIGS.2C-2D) preferably comprises a low temperature superconductor material,substantially as previously described for superconducting layer 22 (FIG.1C-1D).

The SMES system 24 (FIG. 2A) also includes a SMES magnet 38 (FIG. 2A)suspended within the inner vessel 30 (FIG. 2A) immersed in the cryogenicfluid 34 (FIG. 2A). The SMES magnet 38 (FIG. 2A) comprises asuperconductive material coiled around the interface tube 35 (FIG. 2A).In addition, the SMES magnet 38 (FIG. 2A) includes an input/outputelectrical connector 50 (FIG. 2A) on the interface tube 35 (FIG. 2A) fortransferring electrical energy into or out of the SMES magnet 38 (FIG.2A).

The SMES system 24 (FIG. 2A) can also include a portable recharger 42(FIG. 2A) configured to recharge the cryogenic container 26 (FIG. 2A)with the cryogenic fluid 24 (FIG. 2A). The recharger 42 (FIG. 2A) can beconfigured for removable sealed engagement with a fill port 52 (FIG. 2A)on the interface tube 35 (FIG. 2A). In addition, the recharger 42 (FIG.2A) can include a compressor (not shown) configured to compress acryogenic gas to a high pressure (e.g., 1000 to 3000 psig) for injectioninto the cryogenic container 26 (FIG. 2A) to form the cryogenic fluid 34(FIG. 2A). The recharger 42 (FIG. 2A) can also include a passive coolingelement such as a cold finger (not shown) to facilitate transfer of thepressurized cryogenic gas into the fill port 52 (FIG. 2A) on theinterface tube 35 (FIG. 2A).

The SMES system 24 (FIG. 2A) can also include an active portablecryocooler 40 (FIG. 2A) configured to cool a fluid to a cryogenictemperature, and to transfer the fluid 34 to the recharger 42 (FIG. 2A).The cryocooler 40 (FIG. 2A) can also include a power supply (not shown),such as a 12 volt DC battery, for supplying energy for cooling thefluid. In addition, the cryocooler 40 (FIG. 2A) can include a heatexchanger (not shown) and a Joule-Thompson expansion valve (not shown)for cooling the fluid, and a fitting for removably coupling thecryocooler 40 (FIG. 2A) to the recharger 42 (FIG. 2A).

The SMES system 24 (FIG. 2A) can be used in any application requiringportable energy from handheld electronics to supply energy for vehicles.For example, the SMES system 24 (FIG. 2A) can be used as a power sourcefor a alternative fueled vehicle (AFV). In this case, the cryogenicfluid 34 (FIG. 2A) can comprise liquid hydrogen, the cryocooler 40 (FIG.2A) can be adapted to form supercritical hydrogen, and the recharger 42(FIG. 2A) can be adapted to form compressed hydrogen gas. By way ofexample and not limitation, the SMES system 24 (FIG. 2A) can beconfigured to provide a SMES current of about 1000 A, a stored energy ofabout 2.1 MJ (amp hrs), an average power of about 200 kW, a carry overtime of >8 seconds, a DC link voltage of up to 800 V, a magnetic fieldof 4.5 T, an inductivity of 4.1 H, and a magnet diameter of 760 mm/600mm.

As shown in FIG. 3, the SMES magnet 38 includes a plurality ofsuperconducting accumulator coils 46. Each accumulator coil 46 includesa plurality of coil segments 48 joined together and electricallyconnected to form the accumulator coil 46. In addition, each accumulatorcoil can comprise wires or layers formed of a superconductor material.One superconducting wire material comprises SiC doped MgB₂. Thismaterial has been used to develop superconducting magnets by theInstitute for Superconducting and Electronic Materials, University ofWollongong, Wollongong, NSW 2522 Australia.

As also shown in FIG. 3, the SMES magnet 38 can include controlcircuitry 54 configured to either extract energy from the SMES magnet38, or input energy into the SMES magnet 38. For example, in a chargingmode the control circuitry 54 allows the SMES magnet to store energy,and in a discharge mode the control circuitry 54 allows the SMES magnet38 to discharge energy.

The SMES system 24 (FIG. 2A) can also include additional sensors andcircuitry on various elements of the cryogenic container 26 and withinthe interface tube 35. For example, additional sensors and circuitry(e.g., watt meter) can be used for measuring current and voltage inputor output. Additional sensors and circuitry can also be used to measureheat transfer (i.e., MLI contact resistance, support structureconduction, free molecular gaseous conduction) with and withoutsuperconductivity, with temperature sensors placed in the insulation 33and on various other surfaces. In addition, sensors and circuitry can beused to take boil off measurements of the cryogenic fluid 34. Althoughthe sensors and circuitry would generate additional thermal energy, thesystem 24 can be configured to dissipate and mitigate the affects ofthis additional thermal energy.

Referring to FIG. 4, broad steps in the method of the invention areillustrated. These steps include providing the cryogenic container 10adapted to contain the cryogenic fluid 16 at a selected temperaturerange; providing the superconducting layer 22 on the cryogenic container10 having superconductive properties at the selected temperature range;and shielding the cryogenic fluid from electromagnetic energy using thesuperconducting layer 22.

Thus the invention provides a cryogenic container, a SMES system and amethod for shielding a cryogenic fluid. While the invention has beendescribed with reference to certain preferred embodiments, as will beapparent to those skilled in the art, certain changes and modificationscan be made without departing from the scope of the invention as definedby the following claims.

1. A cryogenic container comprising: an inner vessel configured tocontain a cryogenic fluid at a selected temperature range; an outervessel surrounding the inner vessel; and a material lining a surface ofthe inner vessel having superconducting properties at the selectedtemperature range configured to shield the cryogenic fluid in the innervessel from thermal energy transmitted through the inner vessel.
 2. Thecryogenic container of claim 1 further comprising: a rechargerconfigured to inject a compressed cryogenic gas into the inner vesselfor recharging the cryogenic fluid; and a cryocooler configured tosupply the recharger with a fluid.
 3. The cryogenic container of claim 2wherein the fluid comprises hydrogen.
 4. The cryogenic container ofclaim 2 wherein the fluid comprises supercritical hydrogen.
 5. Thecryogenic container of claim 1 wherein the inner vessel is configured tocontain a volume of from 10 cc (cubic centimeters) to 1 m³ (cubicmeters) of the cryogenic fluid.
 6. The cryogenic container of claim 1wherein the material comprises a low temperature superconductor.
 7. Acryogenic container comprising: an inner vessel configured to contain acryogenic fluid at a selected temperature range; an outer vesselsurrounding the inner vessel forming an annulus between the inner vesseland the outer vessel; and a layer on the inner vessel comprising amaterial having superconducting properties at the selected temperaturerange configured to shield the cryogenic fluid in the inner vessel fromthermal energy and infrared radiation transmitted through the innervessel to the cryogenic fluid.
 8. The container of claim 7 wherein thelayer substantially covers an outer surface of the inner vessel.
 9. Thecontainer of claim 7 wherein the layer substantially covers an innersurface of the inner vessel.
 10. The container of claim 7 wherein theinner vessel is adapted to contain a volume of from 10 cc (cubiccentimeters) to 1 m³ (cubic meters) of the cryogenic fluid.
 11. Thecontainer of claim 7 wherein the annulus contains a thermal insulationand a vacuum.
 12. The container of claim 7 wherein the materialcomprises a low temperature superconductor.
 13. The container of claim 7wherein the material comprises a compound selected from the groupconsisting of magnesium diboride, a niobium alloy, a copper oxide, a BCSsuperconductor, a rare earth copper oxide (RECuOx), a carbon material,or a ceramic material.
 14. The container of claim 7 wherein the materialcomprises magnesium diboride.
 15. A system for storing electrical energycomprising: an inner vessel configured to contain a cryogenic fluid at aselected temperature range; an outer vessel surrounding the inner vesselforming an annulus between the inner vessel and the outer vessel; amaterial on the inner vessel having superconducting properties at theselected temperature range configured to shield the cryogenic fluid inthe inner vessel from thermal energy transmitted through the innervessel; a superconducting magnetic energy storage (SMES) magnet in theinner vessel configured to store the electrical energy; and a controlcircuitry configured to either input or extract the electrical energyfrom the (SMES) magnet.
 16. The system of claim 15 further comprising arecharger configured to inject a compressed cryogenic gas into the innervessel for recharging the cryogenic fluid.
 17. The system of claim 16further comprising a cryocooler configured to supply the recharger witha fluid.
 18. The system of claim 17 wherein the fluid comprises asupercritical fluid.
 19. The system of claim 17 wherein the fluidcomprises supercritical hydrogen.
 20. The system of claim 15 wherein thematerial is not permanently attached to the inner vessel.
 21. A methodfor shielding a cryogenic fluid comprising: providing a cryogeniccontainer comprising an outer vessel, and an inner vessel adapted tocontain the cryogenic fluid at a selected temperature range; providing amaterial on the inner vessel having superconductive properties at theselected temperature range configured to shield the cryogenic fluid inthe inner vessel from electromagnetic energy transmitted through theinner vessel; and shielding the cryogenic fluid from the electromagneticenergy using the material.
 22. The method of claim 21 wherein thematerial substantially covers an outer surface of the inner vessel. 23.The method of claim 21 wherein the material substantially covers aninner surface of the inner vessel.
 24. The method of claim 21 whereinthe cryogenic container includes an annulus and the annulus contains athermal insulating material and a vacuum.
 25. The method of claim 21wherein the cryogenic container includes an annulus and the annuluscontains a thermal insulating material.
 26. The method of claim 21wherein the material comprises magnesium diboride.
 27. The method ofclaim 21 wherein the material comprises a compound selected from thegroup consisting of magnesium diboride, a niobium alloy, a copper oxide,a BCS superconductor, a rare earth copper oxide (RECuOx), a carbonmaterial, or a ceramic material.
 28. The method of claim 21 wherein theinner vessel is configured to contain a volume of from 10 cc (cubiccentimeters) to 1 m³ (cubic meters) of the cryogenic fluid.